C# WinForm 下载文件示例

使用 HttpWebRequest 下载文件，参考代码

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;namespace WinShowDown{    public partial class FrmMain : Form    {        public FrmMain()        {            InitializeComponent();        }        private void btnDown_Click(object sender, EventArgs e)        {            DownloadFile("http://localhost:1928/WebServer/downloader/123.rar", @"C:\123.rar", progressBar1, label1);        }        /// <summary>                /// c#,.net 下载文件                /// </summary>                /// <param name="URL">下载文件地址</param>        /// <param name="Filename">下载后的存放地址</param>                /// <param name="Prog">用于显示的进度条</param>        public void DownloadFile(string URL, string filename, System.Windows.Forms.ProgressBar prog, System.Windows.Forms.Label label1)        {            float percent = 0;            try            {                System.Net.HttpWebRequest Myrq = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(URL);                System.Net.HttpWebResponse myrp = (System.Net.HttpWebResponse)Myrq.GetResponse();                long totalBytes = myrp.ContentLength;                if (prog != null)                {                    prog.Maximum = (int)totalBytes;                }                System.IO.Stream st = myrp.GetResponseStream();                System.IO.Stream so = new System.IO.FileStream(filename, System.IO.FileMode.Create);                long totalDownloadedByte = 0;                byte[] by = new byte[1024];                int osize = st.Read(by, 0, (int)by.Length);                while (osize > 0)                {                    totalDownloadedByte = osize + totalDownloadedByte;                    System.Windows.Forms.Application.DoEvents();                    so.Write(by, 0, osize);                    if (prog != null)                    {                        prog.Value = (int)totalDownloadedByte;                    }                    osize = st.Read(by, 0, (int)by.Length);                    percent = (float)totalDownloadedByte / (float)totalBytes * 100;                    label1.Text = "当前补丁下载进度" + percent.ToString() + "%";                    System.Windows.Forms.Application.DoEvents(); //必须加注这句代码，否则label1将因为循环执行太快而来不及显示信息                }                so.Close();                st.Close();            }            catch (System.Exception)            {                throw;            }        }    }}

使用 WebClient 组件下载文件，参考代码

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Diagnostics;using System.Drawing;using System.IO;using System.Linq;using System.Net;using System.ServiceProcess;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace Test{    public partial class FormTest : Form    {        private WebClient webClient1 = new WebClient();        public FormTest()        {            InitializeComponent();            #region 给 webClient1 绑定事件            {                this.webClient1.DownloadFileCompleted += new AsyncCompletedEventHandler(this.webClient1_DownloadFileCompleted);                this.webClient1.DownloadProgressChanged += new DownloadProgressChangedEventHandler(this.webClient1_DownloadProgressChanged);            }            #endregion        }        /// <summary>        /// 下载文件        /// </summary>        private void DownloadFile()        {            // 异步下载文件，可以显示下载进度            // 如果下载失败或资源有问题等将发生异常            this.webClient1.DownloadFileAsync(new Uri(url), this.fullName);        }        // 文件正在下载时发生        private void webClient1_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)        {            // 显示下载进度            if (this.progressBar1.InvokeRequired)            {                this.progressBar1.Invoke(new Action<object, DownloadProgressChangedEventArgs>(this.webClient1_DownloadProgressChanged), sender, e);            }            else            {                this.progressBar1.Value = e.ProgressPercentage;            }        }        // 文件下载成功时发生        private void webClient1_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)        {            // 文件下载成功后执行代码        }    }}